Tinnitus

Pathophysiology

Tinnitus can be described as a patient having the sensation of hearing buzzing, hissing, cricket-like sounds, ringing, whistling, humming or a combination of these.​ It can also present as continuous, intermittent or pulsatile tinnitus.​Tinnitus can have a major impact on quality of life; patients may experience frustration, annoyance, insomnia, anxiety, depression, irritation and difficulty concentrating, in addition to the “ringing in the ears.”​ Although tinnitus can occur at any age, it is less common in children and most common in the elderly. Hearing loss is the most important risk factor for development of tinnitus.​

Tinnitus can be classified into 2 major categories: objective tinnitus, which is caused by a sound produced within the head, and subjective tinnitus (more common), which is the perception of sound or noise without any external stimulation.

Causes of tinnitus include:​

• Objective:
  • mechanical/neurologic, e.g., palatal myoclonus, patulous eustachian tube, tensor tympani myoclonus, idiopathic stapedial muscle spasm
  • spontaneous, e.g., spontaneous otoacoustic emissions
  • vascular/pulsatile, e.g., arteriovenous malformations, carotid stenosis, valvular heart disease, states of high cardiac output, vascular tumor, arterial bruit or other conditions causing turbulent blood flow
• Subjective:
  • drug-related: ototoxic medications or substances, e.g., adverse effect of aminoglycosides, loop diuretics, salicylates
  • infectious, e.g., otitis media, sequelae of meningitis or Lyme disease
  • metabolic, e.g., hyperlipidemia, thyroid dysfunction, vitamin B₁₂ deficiency
  • neurologic, e.g., head injury/whiplash, multiple sclerosis, tumor
  • otologic, e.g., noise-induced hearing loss, impacted cerumen, Meniere disease, presbycusis
  • psychogenic, e.g., depression, anxiety, fibromyalgia
  • other, e.g., temporomandibular-joint dysfunction

The pathophysiology of tinnitus is incompletely understood; however, central mechanisms are involved. A distributed tinnitus brain network, including sensory auditory areas and cortical regions involved in perceptual, emotional, attentional and salience functions, has been hypothesized.​^​

Goals of Therapy

• Treat underlying medical condition, if possible
• Correct hearing loss, if correctable
• Reduce or eliminate tinnitus, although this is not usually possible
• Improve patient’s quality of life

Patient Assessment

Assess and address any potential drug-related causes of tinnitus.​Review the patient’s drug history, both current and past, for potentially ototoxic drugs . Reassess the need for any ototoxic drug found; removal of the offending agent may resolve tinnitus.​ All patients with tinnitus lasting >24 hours, pulsatile, unilateral hearing loss, or history of ear disease or procedures should be assessed by an appropriate health-care practitioner. The severity of tinnitus and the impact on quality of life should be assessed. T

Nonpharmacologic Therapy

• Recommend avoiding loud noises and using noise protectors if loud noise cannot be avoided.
• Recommend using hearing aids and cochlear implants in patients with hearing loss.​
• Recommend cognitive behavioural therapy (CBT).​CBT is sometimes combined with tinnitus retraining therapy, a multidisciplinary program to habituate patients to the sounds of tinnitus.​
• Suggest using sound therapy (e.g., masking techniques or sound-generating devices, where an external noise is used to cover the tinnitus).​ However, a Cochrane review found no evidence to support superiority of this treatment modality over control groups (placebo, wait list, education).​
• Suggest stress management and biofeedback techniques.
• Suggest trial of avoiding or reducing caffeine and nicotine; however, minimal evidence is available to support this recommendation.
• Note: acupuncture has not been proven to be of benefit.​

Pharmacologic Therapy

Many drugs have been studied in the management of tinnitus, including alprazolam, anticonvulsants (carbamazepine, flunarizine, gabapentin, lamotrigine), baclofen, betahistine, melatonin, SSRIs, tricyclic antidepressants and zinc; none have been shown to be effective.

Ginkgo biloba has been studied in the management of tinnitus and is commonly used;​ however, evidence of efficacy is lacking Adverse effects of ginkgo biloba include mild GI complaints, headache, dizziness, palpitations and allergic skin reactions. It is also associated with bleeding and seizures. The risk of bleeding may increase when ginkgo biloba is combined with warfarin or antiplatelet drugs. Advise patients to avoid this combination.

Other natural health products (e.g., maritime pine bark, melatonin, vinpocetine) are purported to be useful for tinnitus, but no evidence is available to confirm or refute any potential benefit.​

Although some patients suffering from tinnitus may use cannabis to treat their symptoms, there is no evidence to support this. Furthermore, there is some animal data to suggest that tinnitus may be exacerbated.​

Monitoring of Therapy

Most trials indicate that drugs will have little benefit in the management of tinnitus. If a drug trial is elected despite this, determine with the patient a stopping time if no improvement is seen. While there is no evidence to guide how long a drug should be tried, clinical trials ran from 6–14 weeks